Field of the Invention
The present invention relates to a transdermal drug delivery device, especially to a transdermal drug delivery device which may deliver injectable drug to the subcutaneous tissue for treatment.
Description of the Related Art
The global injectable drug delivery market was valued at $22.5 billion in 2012; it is expected to reach $43.3 billion by 2017 at a CAGR of 14.0% from 2012 to 2017, according to the report of Injectable Drug Delivery Market by Formulations, Devices & Therapeutics—Global Forecasts to 2017. The injectable drug delivery technologies market is broadly categorized into two major segments, namely, devices technologies and formulation technologies. Based on product, the injectable drug delivery devices technologies market is further categorized into conventional injection devices, self injection devices, and others (microneedles, nanoneedles and blunt needle injections), while injectable drug delivery formulation technologies market is categorized into conventional drug delivery formulations and novel drug delivery formulations. Conventional injection devices segment accounted for the largest share of the overall injectable drug delivery technologies market in 2012.
In addition, the market is segmented on the basis of its therapeutic applications such as auto immune diseases, hormonal imbalances, oncology, orphan/rare diseases (Hemophilia, Ribose-5-phosphate isomerase deficiency (RPI deficiency), Cystic Fibrosis, and Wilson's disease) and others (pain management, allergies, hepatitis C, and aesthetic treatment). Hormonal disorders commanded the largest share of 50.0% of the global injectable drug delivery market in 2012; it is expected to grow at a CAGR of 13.9% to reach $21.6 billion by 2017. However, auto-immune diseases are the fastest growing segment of this market due to the advent of biologics (tumor necrosis factor (TNF) and Interleukin 1 (IL-1)) and improving patient compliance by the development of self injection devices. As per The American Autoimmune Related Diseases Association, 50 million Americans or 20% of the population or one in five people, are living and managing with auto immune diseases during the year 2013.
The major geographic markets of the injectable drug delivery technologies are North America, Europe, Asia-Pacific, and Rest of the World (RoW). North America dominates the market, followed by Europe. However, Asian and Latin American countries represent the fastest growing markets due to growing number of cancer and diabetes incidences.
In addition, the outbreaks of highly pathogenic avian influenza in Asia for the past few years and spread of the disease worldwide highlight the need to redefine conventional immunization approaches and establish effective mass vaccination strategies to face global pandemics. Vaccination is one of approaches to fight infectious diseases and deaths. The conventional vaccination approach is an invasive method that has disadvantages such as sometimes it is painful for the person, it is required to carry out the injection by medical personnel or professional personnel, the injectable drug delivery is always connected with a risk of infection, and storage and transportation of the vaccine. Transcutaneous immunization (TCI) is a novel route for vaccination, which uses the topical application of vaccine antigens on the skin that can enhance medicine effectiveness and improve patient compliance.
Therefore, the transdermal drug delivery device is worth further developing. Typically, the transdermal drug delivery device has microneedle array that is formed by high precision machining technology, e.g., precision stamping, ion etching, sand blast laser, X-ray laser cutting, lithography, coupled plasma, electrocasting technology. The length of the microneedles typically is about tens of micrometers. The transdermal microneedle drug delivery device with minimally invasive piercing can effectively reduce the pain of the users to achieve an injection without pain almost.
In current application, cosmetic surgery using derma roller, also called microneedling therapy system (MTS), is a minimally invasive skin-rejuvenation procedure that involves the use of a device that contains fine needles. The needles are used to puncture the skin to create a controlled skin injury. Each puncture creates a channel that triggers the body to fill these microscopic wounds by producing new collagen and elastin. Through the process of neovascularization and neocollagenesis, there is improvement in skin texture and firmness, as well as reduction in scars, pore size, and stretch marks.
The traditional medical drug delivery technology has its limitations, such as oral dosing is the most convenient and cheapest way, but the medical drug absorption is interfered by diet and other drug. Also, the absorbed dose of the medical drug is reduced due to hepatic metabolism. As to intravenous injection, the drug delivery may be fast and accurate, but it is required to provide by the professional and painful for patients. In medical applications, the transdermal drug delivery device with microneedle array can deliver drugs through the skin, and can penetrate drugs through the skin into the bloodstream, is a very attractive and new drug delivery technology.
The array-arranged microneedles of a transdermal drug delivery device can be manufactured with standard semiconductor process such as photolithograph process and etching process. The related art disclosed a process for manufacturing silicon microneedles. Firstly a silicon wafer with a first patterned photoresist layer is prepared. Next, a through hole is defined on the wafer by anisotropic etching. Afterward, a chromium layer is coated on the wafer and a second patterned photoresist layer is formed atop the through hole to function as circular etching mask. Next, the wafer is then etched to form outer tapered wall for the microneedles. However, the silicon-based microneedles are brittle and tend to break when the microneedles prick through user's skin.
Alternatively, hollow microneedles with resin barbules are proposed, where the barbules are drilled by laser processing. Firstly, sheet with barbules is formed by extruding polyimide or polyether ether ketone, and then the barbules are drilled by laser to form hollow microneedles. However, the microneedles have compact size such that the barbules may have ragged edge after extrusion. Moreover, it is difficult to form a hollow microneedle with off-axis through hole or central through hole having uniform inner diameter by laser processing.
In summary, there is a need to provide a transdermal drug delivery device which may deliver injectable drug to the subcutaneous tissue for treatment. The microneedle of the transdermal drug delivery device can be kept intact after the microneedle pricks user's skin for drug delivery.